Id2 Represses Aldosterone-Stimulated Cardiac T-Type Calcium Channels Expression

Aldosterone excess is a cardiovascular risk factor. Aldosterone can directly stimulate an electrical remodeling of cardiomyocytes leading to cardiac arrhythmia and hypertrophy. L-type and T-type voltage-gated calcium (Ca2+) channels expression are increased by aldosterone in cardiomyocytes. To further understand the regulation of these channels expression, we studied the role of a transcriptional repressor, the inhibitor of differentiation/DNA binding protein 2 (Id2). We found that aldosterone inhibited the expression of Id2 in neonatal rat cardiomyocytes and in the heart of adult mice. When Id2 was overexpressed in cardiomyocytes, we observed a reduction in the spontaneous action potentials rate and an arrest in aldosterone-stimulated rate increase. Accordingly, Id2 siRNA knockdown increased this rate. We also observed that CaV1.2 (L-type Ca2+ channel) or CaV3.1, and CaV3.2 (T-type Ca2+ channels) mRNA expression levels and Ca2+ currents were affected by Id2 presence. These observations were further corroborated in a heart specific Id2- transgenic mice. Taken together, our results suggest that Id2 functions as a transcriptional repressor for L- and T-type Ca2+ channels, particularly CaV3.1, in cardiomyocytes and its expression is controlled by aldosterone. We propose that Id2 might contributes to a protective mechanism in cardiomyocytes preventing the presence of channels associated with a pathological state.

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Evidence for functional sodium and calcium ion channels in the membrane of cultured cardiomyocytes of the adult rat

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y83-189 ◽

1983 ◽

Vol 61 (11) ◽

pp. 1312-1316 ◽

Cited By ~ 5

Author(s):

S. L. Jacobson ◽

C. B. Kennedy ◽

G. A. R. Mealing

Keyword(s):

Action Potentials ◽

Rat Cardiomyocytes ◽

Adult Rat ◽

Culture Cells ◽

Calcium Ion Channels ◽

Spontaneous Action ◽

Fetal Bovine ◽

Spontaneous Action Potentials

Characteristics are reported for electrical activity of adult rat cardiomyocytes in long-term primary culture. Cells in vitro for 12 to 28 days have mean membrane potential of −53 mV, are electrically excitable, and some are spontaneously contractile. The action potential of these cells has a slow rate of depolarization and is abolished by methoxyverapamil (D-600) but not by tetrodotoxin (TTX). When cells are hyperpolarized by passage of an inward current, spontaneous action potentials cease and action potentials evoked by depolarizing pulses are then TTX sensitive. Fetal bovine serum is a constituent of the culture medium. Its temporary removal causes spontaneous contractility to cease but the cells remain electrically excitable.

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RBM20 Regulates CaV1.2 Surface Expression by Promoting Exon 9* Inclusion of CACNA1C in Neonatal Rat Cardiomyocytes

International Journal of Molecular Sciences ◽

10.3390/ijms20225591 ◽

2019 ◽

Vol 20 (22) ◽

pp. 5591 ◽

Cited By ~ 1

Author(s):

Morinaga ◽

Ito ◽

Niimi ◽

Maturana

Keyword(s):

Alternative Splicing ◽

Heart Development ◽

Rna Binding ◽

Surface Expression ◽

Neonatal Rat ◽

Sequencing Analysis ◽

Rat Cardiomyocytes ◽

Neonatal Rat Cardiomyocytes ◽

Exon 9 ◽

Sirna Knockdown

The CACNA1C gene encodes for the CaV1.2 protein, which is the pore subunit of cardiac l-type voltage-gated calcium (Ca2+) channels (l-channels). Through alternative splicing, CACNA1C encodes for various CaV1.2 isoforms with different electrophysiological properties. Splice variants of CaV1.2 are differentially expressed during heart development or pathologies. The molecular mechanisms of CACNA1C alternative splicing still remain incompletely understood. RNA sequencing analysis has suggested that CACNA1C is a potential target of the splicing factor RNA-binding protein motif 20 (RBM20). Here, we aimed at elucidating the role of RBM20 in the regulation of CACNA1C alternative splicing. We found that in neonatal rat cardiomyocytes (NRCMs), RBM20 overexpression promoted the inclusion of CACNA1C’s exon 9*, whereas the skipping of exon 9* occurred upon RBM20 siRNA knockdown. The splicing of other known alternative exons was not altered by RBM20. RNA immunoprecipitation suggested that RBM20 binds to introns flanking exon 9*. Functionally, in NRCMs, RBM20 overexpression decreased l-type Ca2+ currents, whereas RBM20 siRNA knockdown increased l-type Ca2+ currents. Finally, we found that RBM20 overexpression reduced CaV1.2 membrane surface expression in NRCMs. Taken together, our results suggest that RBM20 specifically regulates the inclusion of exon 9* in CACNA1C mRNA, resulting in reduced cell-surface membrane expression of l-channels in cardiomyocytes.

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The increase of extracellular Ca2+ from physiological concentrations to hypercalcemia impairs sino-atrial automaticity

EP Europace ◽

10.1093/europace/euab116.567 ◽

2021 ◽

Vol 23 (Supplement_3) ◽

Author(s):

AG Torrente ◽

L Fossier ◽

M Baudot ◽

E Torre ◽

I Bidaud ◽

...

Keyword(s):

Action Potentials ◽

Ex Vivo ◽

Pacemaker Activity ◽

Funding Source ◽

Cell Contractility ◽

Funding Sources ◽

Spontaneous Action ◽

Spontaneous Action Potentials ◽

Ca2 Channels ◽

Funding Acknowledgements

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): ESC FRM Lefoulon Delalande Aims To investigate whether extracellular hypercalcemia alters the conduction through L-type Ca2+ channels (LTCCs), impairing the pacemaker activity of the heart. Introduction In the sino-atrial node (SAN), membrane currents and the dynamics of intracellular Ca2+ ([Ca2+]i) generate the pacemaker activity of the heart. SAN dysfunctions (SNDs) harm heart automaticity and have been associated with abnormal dynamics of [Ca2+]i. The LTCCs, Cav1.2 and Cav1.3 carry the main Ca2+ influx of SAN cells, which is necessary to sustain [Ca2+]i dynamics. Modified extracellular Ca2+ ([Ca2+]o) could alter Ca2+ influx through these channels. For example, cancer and hyperparathyroidism can raise [Ca2+]o, causing an extracellular hypercalcemia that could alter [Ca2+]i dynamics and impair SAN activity and heart automaticity. Methods and results To test this hypothesis, we measured contractions, [Ca2+]i release and L-type Ca2+ current (ICa,L) in spontaneous cells of the murine SAN. Then, we recorded rate and propagation of the spontaneous action potentials (APs) generated by the SAN tissue ex-vivo. In spontaneously beating SAN cells, we observed that the modification of [Ca2+]o affected [Ca2+]i and cell contractility through changes of ICa,L. In particular, the increase of [Ca2+]o dysregulated pacemaker activity, likely through excessive Ca2+ influx mediated by Cav1.2. [Ca2+]o increase to hypercalcemia induced arrhythmia also in the intact SAN tissues, activating ectopic leading regions of pacemaking and impairing conduction towards the atria. Conclusions Hypercalcemia causes excessive Cav1.2-mediated Ca2+ influx, which alters [Ca2+]I leading to pacemaker impairment. Modulation of LTCC may reduce pacemaker dysfunctions, preventing SND progression.

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TAFII250, Egr-1, and D-type cyclin expression in mice and neonatal rat cardiomyocytes treated with doxorubicin

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1999.276.3.h803 ◽

1999 ◽

Vol 276 (3) ◽

pp. H803-H814 ◽

Cited By ~ 4

Author(s):

Nacéra Saadane ◽

Lesley Alpert ◽

Lorraine E. Chalifour

Keyword(s):

Single Injection ◽

Neonatal Rat ◽

Cardiac Damage ◽

Rat Cardiomyocytes ◽

Neonatal Cardiomyocytes ◽

Neonatal Rat Cardiomyocytes ◽

Adult Mice ◽

Factor Ii

Differential display identified that gene fragment HA220 homologous to the transcriptional activator factor II 250 (TAFII250) gene, or CCG1, was increased in hypertrophied rodent heart. To determine whether TAFII250 gene expression is modified after cardiac damage, we measured TAFII250 expression in vivo in mouse hearts after injection of the cardiotoxic agent doxorubicin (DXR) and in vitro in DXR-treated isolated rat neonatal cardiomyocytes. In vivo atrial natriuretic factor (ANF), β-myosin heavy chain (β-MHC), Egr-1, and TAFII250 expression increased with dose and time after a single DXR injection, but only ANF and β-MHC expression were increased after multiple injections. After DXR treatment of neonatal cardiomyocytes we found decreased ANF, α-MHC, Egr-1, and TAFII250 expression. Expression of the TAFII250-regulated genes, the D-type cyclins, was increased after a single injection in adult mice and was decreased in DXR-treated cardiomyocytes. Thus expression of Erg-1, TAFII250, and the D-type cyclins is modulated after cardiotoxic damage in adult and neonatal heart.

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Mechanisms of Vitexin Preconditioning Effects on Cultured Neonatal Rat Cardiomyocytes with Anoxia and Reoxygenation

The American Journal of Chinese Medicine ◽

10.1142/s0192415x08005849 ◽

2008 ◽

Vol 36 (02) ◽

pp. 385-397 ◽

Cited By ~ 15

Author(s):

Liu-Yi Dong ◽

Zhi-Wu Chen ◽

Yan Guo ◽

Xin-Ping Cheng ◽

Xu Shao

Keyword(s):

Protective Effect ◽

Cell Viability ◽

Neonatal Rat ◽

Protective Mechanism ◽

Cellular Injury ◽

Rat Cardiomyocytes ◽

Neonatal Rat Cardiomyocytes ◽

Extracellular Signal ◽

Upstream Kinase ◽

Laser Confocal Microscope

This study was aimed at investigating the protective effect and mechanism of vitexin preconditioning (VPC) on cultured neonatal rat cardiomyocytes after anoxia and reoxygenation (A/R). An A/R model was established by using cultured neonatal rat cardiomyocytes. Cellular injury was evaluated by measuring cell viability, the releases of creatine kinase (CK), and lactate dehydrogenase (LDH). The apoptosis rate of cardiomyocytes after Anoxia/reoxygenation and the activities of extracellular signal-regulated protein kinases (ERKs) were measured. The intracellular calcium indicated by the fluorescence in cardiomyocytes was measured by the laser confocal microscope. Vitexin preconditioning (10, 30 and 100 μM) significantly enhanced the cell viability, markedly inhibited A/R-induced increases of LDH and CK release, obviously decreased the number of apoptotic cardiomyocytes and markedly decreased the fluorescence intensity value of [ Ca2+]iin cardiomyocytes. Exposure to anoxia or vitexin preconditioning significantly increased the phospho-ERK level, and the increase was markedly inhibited by PD98059, an inhibitor of the upstream kinase of ERK. These results suggest that vitexin preconditioning has a protective effect on cardiomyocytes A/R injury through the improvement of cell viability, decrease of LDH and CK release, such that the protective mechanism may relate to its ability to inhibit the cardiomyocytes apoptosis, reduce the cardiomyocytes calcium overload and increase the abundance of phosphor-ERK1/2 of the cardiomyocytes after anoxia and reoxygenation.

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Endothelin-1 Stimulates the Expression of L-Type Ca2+ Channels in Neonatal Rat Cardiomyocytes via the Extracellular Signal–Regulated Kinase 1/2 Pathway

The Journal of Membrane Biology ◽

10.1007/s00232-013-9538-7 ◽

2013 ◽

Vol 246 (4) ◽

pp. 343-353 ◽

Cited By ~ 5

Author(s):

Liangzhu Yu ◽

Mincai Li ◽

Tonghui She ◽

Chunrong Shi ◽

Wei Meng ◽

...

Keyword(s):

Neonatal Rat ◽

Rat Cardiomyocytes ◽

Extracellular Signal Regulated Kinase ◽

Endothelin 1 ◽

Neonatal Rat Cardiomyocytes ◽

Extracellular Signal ◽

Ca2 Channels

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Abstract 15137: β2-adrenergic Signaling Promotes IL-6 Production From Cardiac Fibroblasts Through CREB/Arid5a Pathway and Induces Cardiac Hypertrophy via Paracrine System

Circulation ◽

10.1161/circ.142.suppl_3.15137 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Shota Tanaka ◽

Makiko Maeda ◽

Masanori Obana ◽

Yasushi Fujio

Keyword(s):

Cardiac Hypertrophy ◽

Cardiac Fibroblasts ◽

Neonatal Rat ◽

Rt Pcr ◽

Interaction Domain ◽

Cross Sectional ◽

Rat Cardiomyocytes ◽

Cardiac Inflammation ◽

Adult Mice ◽

Phosphorylated Creb

Background: β-adrenergic receptor (βAR) is involved in cardiac inflammation and hypertrophy. It has been revealed that βAR stimulation induces cardiac hypertrophy not only directly but also indirectly, for example, via cardiac fibroblasts (CFs). Interestingly, βAR signaling promotes the production of interleukin (IL)-6 from CFs. However, it has not been clarified the relationship between IL-6 released from CFs and cardiac hypertrophy after βAR stimulation. Objective: To elucidate the mechanisms by which βAR signaling promotes the production of IL-6 in CFs and the effects of CFs-secreted IL-6 on cardiac hypertrophy. Methods: CFs were isolated from adult mice. The expression of mRNA was measured by quantitative RT-PCR and the secretion of IL-6 into the medium was quantified by ELISA. Cardiac hypertrophy was assessed by echocardiography, cross-sectional area or cell surface area of cardiomyocytes. Results: RT-PCR revealed that β2AR and β3AR, but not β1AR, were mainly expressed in CFs. Salbutamol (SAL), a selective β2AR agonist, increased IL-6 mRNA by 20-fold, whereas CL-316243, a selective β3AR agonist, did only negligibly. Moreover, SAL, not CL-31243, upregulated the mRNA expression of AT-rich interaction domain 5A (Arid5a), an IL-6 mRNA stabilizing factor, by 4 times. CFs from Arid5a -null mice exhibited reduced expression of IL-6 mRNA and protein, compared with wild-type (WT) CFs, with or without SAL. SAL phosphorylated CREB, suggesting that SAL activated CREB pathway. The compound 666-15, a CREB inhibitor, suppressed SAL-induced IL-6 and Arid5a upregulation. Importantly, WT and IL-6 -null mice were continuously treated with isoproterenol (ISO), a non-selective βAR agonist, for 2 weeks. Cardiac dilatation and cardiomyocyte enlargement were induced by chronic ISO treatment in WT mice, but to lesser extent in IL-6 -null mice. Finally, conditioned media from WT CFs treated with ISO enlarged cultured neonatal rat cardiomyocytes by 10%, while not those from IL-6 -null CFs. Conclusion: β2AR signaling induced IL-6 via CREB/Arid5a axis in CFs. Moreover, CFs-secreted IL-6 contributed to the enlargement of cardiomyocytes through paracrine signaling. β2AR signaling in CFs could be a therapeutic target against cardiac hypertrophy.

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